Active Query Sensing for Mobile Location Search

Back to Project List



While much exciting progress is being made in mobile visual search, one important question has been left unexplored in all current systems. When the first query fails to find the right target (up to 50% likelihood), how should the user form his/her search strategy in the subsequent interaction? We propose a novel Active Query Sensing system to suggest the best way for sensing the surrounding scenes while forming the second query for location search. This work may open up an exciting new direction for developing interactive mobile media applications through innovative exploitation of active sensing and query formulation.fig1

Our proposed framework is general. It can be extended and applied to mobile visual search of targets of multi-view references, such as the example shown below.fig1

System Architecture

The basic idea of AQS is to use the first query as "probe" to narrow down the solution space. And the subsequent query views should be chosen in order to maximally reduce the location search uncertainty. We accomplish the goal by developing several unique components – an offline process for analyzing the saliency of the views associated with each geographical location based on score distribution modeling, predicting the visual search precision of individual views and locations, an online process for estimating the view of an unseen query, and suggesting the best subsequent view change. fig1

Performance Evaluation

The figure below shows failure rates over successive query iterations based on different active query sensing strategies. Using a scalable visual search system implemented over a NYC street view data set (0.3 million images), we show the proposed method (the curve with label "Saliency") can achieve a performance gain as high as two folds, reducing the failure rate of mobile location search from 28% to only 12% after the second query. fig1

User Interface

We have implemented an end-to-end complete prototype for the proposed AQS system, including an iPhone mobile client, communication modules, and the image matching and retrieval server. The interfaces allow users to visualize search results by combining both panorama image and map. We have also designed an intuitive mechanism to show the user the best view angle and required camera rotation when taking the next query. Snapshots of the mobile user interfaces are shown below.



We would like to thank NAVTEQ for providing the NYC image data set, Dr. Xin Chen and Dr. Jeff Bach for their generous help.


Felix X. Yu, Rongrong Ji, Tongtao Zhang, Shih-Fu Chang


  1. Felix X. Yu, Rongrong Ji, Shih-Fu Chang. Active Query Sensing for mobile location search. In Proceeding of ACM International Conference on Multimedia (ACM MM), 2011. details  [Slides] [Poster]
  2. Felix X. Yu, Rongrong Ji, Tongtao Zhang, Shih-Fu Chang. A mobile location search system with Active Query Sensing. In Proceeding of ACM International Conference on Multimedia (ACM MM), 2011. details  [Demo Video] [Poster]